C509-L_97 Datasheet, PDF (33/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Memory Organization
C509-L
3.4.5 Programming Mode Configuration
The External Programming Mode is implemented for the in-circuit programming of external 5V-only
FLASH EPROMs. Similar as in the XRAM mode, the Boot ROM, the XRAM, and the external data
memory (SRAM) are mapped into the code memory area, while the external FLASH memory is
mapped into the external data memory area. Additionally to the XRAM mode, the FLASH memory
can also be written through external data memory accesses (MOVX instructions). External program
memory fetches from the SRAM are controlled by the P3.7/RD/PSENX pin. External data memory
read/write accesses from/to the ROM/EPROM are controlled by the PSEN/RDF and P6.3/WRF pin.
The Programming Mode is entered by setting the bits PRGEN1 and SWAP in SFR SYSCON1. The
locations of the code- and data memory in the Programming Mode are shown in figure 3-6.
Figure 3-6
Locations of Code- and Data Memory in Programming Mode
Prior to the usage of the Programming Mode, the XRAM has to be loaded by the FLASH specific
programming software algorithms (see also chapter 10 “The Bootstrap Loader”). This XRAM load
operation can be done using the Bootstrap Mode.
Semiconductor Group
3-8
1997-10-01